In this study, a new method of bonding CFRP and Al6061-T6 with epoxy adhesive after shot-peening treatment on the surface of Al6061-T6 specimens was proposed to improve bonding strength of a single lap joint between CFRP and Al6061-T6. More specifically, correlation between shot peening coverage on the Al6061-T6 surface and bonding strength with CFRP was experimentally analyzed. Experimental results showed that the surface roughness and the bonding strength increased as the peening time on the surface of Al6061-T6 increased up to a specific peening time (or coverage). However, the surface roughness and bonding strength decreased again under an over-peening condition of 480 seconds (300% coverage) or more. Therefore, it is necessary to search for the optimal peening time that can maximize bonding strength as well as the fatigue life of parts at a peening time between 320 (200%) and 480 s (300%) through additional experiments in future studies.

In this study, laser transmission welding of two heterogeneous polymeric materials was performed and the effect of laser process parameters on the weld joint strength was investigated by shear test corresponding to ASTM standard D3163-01. Specifically, laser transmission welding of 2 ㎜ thick PMMA and PC/ABS was performed using a thulium laser with wavelength and focusing diameter of 2 ㎛ and 1 ㎜, respectively. The experimental results showed that the bonding strength increases as the laser energy transmitted to the welding zone increases, but too strong energy causes a decrease in the mechanical properties of the heat-affected zone. Thus, it is necessary to find the laser process parameters (Maximum Laser Power and Laser Scan Speed) that can secure sufficient bonding strength within the allowable range where surface defects do not occur in the actual process.